Australia's only active volcano is rumbling fiercely, with new NASA photos revealing its lava lake has overflowed its crater.
The volcano in question, Big Ben, is happily located on Mawson Peak in the remote southern reaches of the Indian Ocean on Heard Island, an Australian territory. People only bother to visit Heard and its …

Re: Seen but not Heard

Actually its the Predators firing up their training facility.....

Mysterious multi-billionaire Mr. Weyland is forming a party to investigate the heat signature!

(OK, the "Alien vs. Predator" reference is a bit of a reach considering the mid-range success and quality of that movie, but what else am I going to say? That if this volcano erupts the resulting ash cloud is going to interrupt the globally-vital air corridor between Hobart and McMurdo Station?)

Re: Actually its the Predators firing up their training facility.....

"quality of that movie"

I watched it in a French cinema, with no English subs, with my French ex-girlfriend. Lacking any real skills in the French language, beyond asking for a beer, I could still follow what was happening with the most simplistic of plot ever and even I could tell the film was crap. I've since watched it in English and confirmed that it was indeed crap.

Question that may very well be a silly one, but if the caldera is filled with molten rock to the point where it is overflowing, why is the ice/snow/glacier, especially that covering the caldera and surrounding the place where it is spilling out, still there?

I, for one, am glad you asked

Lava lakes are very rare and there are only four persistent lava lakes on Earth (Nyragongo, Erta Ale, Erebus and Kilauea), so it is quite possible the lava lake has drained back into the volcano and this is erupting through a vent at or around the crater rim. Bearing in mind just where Big Ben is located and the low risk it presents, I doubt any geologists will be hot-footing it there to take a better look.

I believe the caldera is under the cloud (very likely self generated) to the left of the lava flow, while the snow on the rest of the mountain isn't warm enough to melt (yet). The lava flow probably has melted a few feet of snow, but is primarily losing it's heat to the air.

As to wider impacts, ash clouds affecting airlines is unlikely as it is not under a glacier (which was one of the reasons Ejya's ash went so high - I did hear once that the long version of the name is supposedly locals having a laugh, the volcano is Ejya, the glacier is Ejyafyallajokul, but the news carried on using the long name, so not sure if this is apocryphal), an open caldera would usually preclude a large explosion - unless it cools and plugs the magma chamber, then becomes active again, so it's leaning towards an Etna/Kilauea style effusive eruption.

'I did hear once that the long version of the name is supposedly locals having a laugh, the volcano is Ejya, the glacier is Ejyafyallajokul, but the news carried on using the long name, so not sure if this is apocryphal'

The glacier is Eyjafjallajökull (literally the glacier on the mountain overlooking the (Westman) Islands). The south side of the massif on which the glacier is perched containing the volcano is Eyjafjöll proper, but most Icelanders call the whole thing Eyjafjallajökull - unlike the rest of us they don't seem to have problems round about the thirteenth syllable.

This earlier image: http://en.wikipedia.org/wiki/File:ISS018-E-038182_lrg.jpg seems to show the volcano's structure better.

The shadow line at bottom right shows a breached caldera rim with glaciers flowing off to the left. The resurgent cone of Mawson Peak partially fills the caldera. The dark spot at the centre would appear to be the active crater.

There are two craters.

The very big and very obvious one in the Reg article's pic is filled with snow. No molten lava here.

There is a secondary cone rising out of (and obliterating) the rim of the very big and very obvious crater, on the left-bottom part of the big one's rim. At the peak of this secondary cone there is a teensy-weensy little crater which can just be seen as a small black dot on the shadow-line just up and right of the top of the labelled lava flow.